'Preaching' in the Bible

For seeing that in the wisdom of God the world through its wisdom knew not God, it was God's good pleasure through the foolishness of the preaching to save them that believe.

And my speech and my preaching were not in persuasive words of wisdom, but in demonstration of the Spirit and of power:

and if Christ hath not been raised, then is our preaching vain, your faith also is vain.